JP2011032081A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of continuing consistently adequate paper feeding operation while changing a priority to avoid the occurrence of a trouble when a carrying component such as a paper feeding roller deteriorates. <P>SOLUTION: The image forming device includes a priority determining means 136 for determining the priority of a plurality of paper feeding cassettes, if they exist, storing specified required-size paper, a feed executing means 137 for executing paper feed from the highest priority paper feeding cassette of the highest priority out of the priority determined by the priority determining means 136, and a speed detecting means 132 for individually detecting the feeding speed of the paper picked out of each paper feeing cassette. The priority determining means 136 changes the priority of the paper feeding cassettes depending on the magnitude of the paper feeding speed detected by the speed detecting means 132. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms image information on a sheet of paper, and more particularly to an image forming apparatus provided with a plurality of paper feed cassettes for storing paper.

  2. Description of the Related Art Conventionally, an image forming apparatus including a plurality of paper feed cassettes arranged in upper and lower stages is known. The plurality of paper feed cassettes may contain different sizes of paper, respectively. For example, a frequently used size paper such as A4 size is accommodated across the plurality of paper feed cassettes. Sometimes.

  When sheets of the same size are accommodated across a plurality of paper feed cassettes, the user presets a paper feed cassette (hereinafter referred to as the highest priority paper feed cassette) that is fed most preferentially. Be able to. With this setting, in the so-called initial mode such as when the main switch is turned on, at the time of auto clear, or at the time of auto reset, the priority sheet cassette is automatically selected and printing is performed.

  However, when a single paper feed cassette is set as the highest priority paper feed cassette, only the specific highest priority paper feed cassette is used unless the user intentionally changes the priority order in consideration of the deviation of the usage frequency. As a result, problems such as paper feed failure occur due to early wear of transport parts such as pick-up rollers and transport rollers that take out paper from the highest priority paper feed cassette. It becomes easy to do.

  Therefore, conventionally, a technique has been proposed in which the priority order is changed using the number of operations of the paper feed cassette as a guide (for example, see Patent Document 1 below). That is, in this prior art, the number of sheets sent out from the paper cassette is counted as the number of operations, and when this count value exceeds a preset specified value, the priority of the paper cassette is set. The other paper cassette is lowered and set as the highest priority paper cassette so that paper is fed from the newly set highest priority paper cassette.

JP 2005-145582 A

  By the way, in the prior art described in Patent Document 1 described above, the priority order is changed based on the number of operations of the frequently used paper cassette, so that only a specific paper cassette is always used. However, depending on the type of paper and the like, even if the number of operations is small, the wear of conveying parts such as a pickup roller and a conveying roller is promoted relatively early, and durability may deteriorate.

  Therefore, as in the past, if the priority of the paper cassettes is changed by judging the degree of deterioration of transport parts such as the pick-up roller and transport roller using only the number of operations of the paper cassette as a guideline, the actual operation is actually performed. There is a possibility that the paper feeding operation from the paper feeding cassette is still continued even though the transport parts having a small number of times are significantly deteriorated, resulting in a failure.

  The present invention has been made in order to solve the above-described problem. By monitoring the paper feed speed that directly reflects the degree of deterioration of a conveyance component such as an actual pickup roller or conveyance roller, the conveyance component is provided. When an image forming apparatus is deteriorated, it is possible to change the priority order of the sheet feeding cassettes more reliably than in the past to avoid the occurrence of a failure and to provide an image forming apparatus capable of always continuing an appropriate sheet feeding operation. Objective.

  In order to achieve the above object, an image obtained by feeding a recording medium from one of a plurality of recording medium storage units and reading an image from a document on one surface of the recording medium An image forming apparatus that forms information employs the following configuration.

  In other words, the image forming apparatus of the present invention includes a size designation unit that designates the size of the recording medium. In addition, when there are a plurality of recording medium storage units storing the recording medium of the size specified by the size specifying unit, the image forming apparatus determines a priority order for the plurality of recording medium storage units. Priority order determining means is provided. Further, the image forming apparatus performs feeding of the recording medium from the highest priority recording medium storage unit which is the recording medium storage unit with the highest priority among the priority levels determined by the priority level determination unit. A transmission execution means is provided. The image forming apparatus includes a speed detection unit that individually detects the speed of the recording medium fed from each recording medium storage unit in the vicinity of the recording medium storage unit. The priority order determining means changes the priority order of the recording medium storage unit according to the speed of the recording medium detected by the speed detecting means.

  Here, for example, a sheet corresponds to the recording medium. The recording medium storage unit corresponds to, for example, a paper feed cassette. For example, when the recording medium is set to paper, the size of the recording medium corresponds to A3, A4, and the like.

  The size of the recording medium designated by the size designation means is set, for example, when the recording medium is set to paper, the paper size (A3, A4, etc.) input by the user via the operation panel or the like, This corresponds to the size of the paper that is automatically input based on the position of the cursor that regulates the edge of the printed paper and the position detection sensor that detects the position. The size of the recording medium may be, for example, a paper size input from a document size detection sensor set in advance on a document table, or a document restriction cursor provided in advance in a paper feed tray of an automatic document feeder. And the size of the paper input based on the position detection sensor for detecting the position of the cursor. The speed of the recording medium detected by the speed detecting means corresponds to the paper feeding speed when the recording medium is set to paper, for example.

  Further, the priority order determining means sets the highest priority recording medium storage section to the recording medium currently being executed when the speed of the recording medium detected by the speed detecting means is less than a preset specified value. It can be configured to change from the storage unit to the next higher-priority recording medium storage unit.

  In addition, the image forming apparatus includes a feed availability detection unit that determines whether or not feeding from the recording medium storage unit is possible, and the priority order determination unit is configured to detect the highest priority by the feed availability detection unit. When it is determined that feeding from the priority recording medium storage unit is impossible, the highest priority recording medium storage unit is changed from the recording medium storage unit currently being executed to the recording medium storage unit with the next highest priority. It can be configured as follows.

  Furthermore, the image forming apparatus includes a pair of front and rear recording medium passage detection sensors arranged along the conveyance direction of the recording medium taken out from each recording medium storage portion, and the speed detection unit includes the recording medium passage detection sensor. The speed of the recording medium can be detected on the basis of the detection signal obtained by the above and the distance between the pair of front and rear recording medium passage detection sensors.

  In the case of the configuration, the recording medium passage detection sensors are arranged in a pair of front and rear along the conveyance direction of the recording medium taken out from each recording medium storage portion, and the speed detection means is based on the front recording medium passage detection sensor. Based on the detection signal corresponding to the passage of the recording medium and the detection signal corresponding to the passage of the recording medium by the rear recording medium passage detection sensor, the time required for the recording medium to pass through the preceding and following recording medium passage detection sensors is calculated. In addition, the distance between the front and rear recording medium passage detection sensors is divided by the time to detect the speed of the recording medium.

  Further, the speed detection means may be configured to detect the speed of the recording medium using one recording medium passage detection sensor instead of the pair of front and rear recording medium passage detection sensors. For example, only one recording medium passage detection sensor is disposed along the conveyance direction of the recording medium, and the speed detection means is a detection signal corresponding to the front end of the recording medium by the recording medium passage detection sensor, Based on the detection signal corresponding to the rear end of the recording medium, the time required for the entire recording medium to pass at the position where the recording medium passage detection sensor is provided is calculated, and the size of the recording medium in the transport direction is calculated. It may be configured to detect the speed of the recording medium by dividing by the time. The size in the transport direction of the recording medium is specified by the size specifying means, for example. Further, when only one recording medium passage detection sensor is provided, one recording medium passage detection sensor may be provided in the middle of the recording medium conveyance path common to each recording medium storage portion.

  According to the present invention, instead of changing the priority of using a paper feed cassette based on the number of operations of the paper feed cassette as in the prior art, the degree of deterioration of actual parts for conveyance such as a pickup roller and a conveyance roller is changed. When the paper feed speed that directly reflects is monitored and the paper feed speed becomes smaller than a preset specified value, the priority order determining means changes the priority order for using the paper feed cassette. The occurrence of failures can be reduced more reliably than in the past, and appropriate paper feeding operations can be continued at any time.

  In addition, it is determined whether or not the paper feed cassette can be fed by determining whether or not the paper can be fed. If the paper cannot be fed, the priority determining unit changes the priority. Therefore, it is possible to prevent problems such as inability to print or interruption of printing.

  Further, if a configuration including a recording medium passage detection sensor for detecting the front end or the rear end of the paper, which is provided individually in the middle of the paper conveyance path in the vicinity of each paper feed cassette, is provided as the speed detection means. Since the presence / absence of passage of paper for each cassette can be reliably detected, the paper feed speed can be detected with a simple and inexpensive configuration.

1 is a schematic configuration diagram of a digital copying machine according to an embodiment of the present invention. It is a schematic block diagram of the whole control system of the digital copying machine. FIG. 3 is a functional block diagram of a control portion of a paper feeding device provided in the digital copying machine. FIG. 4 is a flowchart illustrating a paper feed processing procedure in the functional block diagram of FIG. 3.

  Hereinafter, the case where the image forming apparatus of the present invention is applied to a digital copying machine will be described, but the present invention is not limited to such a digital copying machine.

<Image forming apparatus>
FIG. 1 is a schematic configuration diagram showing the overall configuration of a digital copying machine according to an embodiment of the present invention.

  The digital copying machine 100 according to this embodiment is mainly composed of an image reading unit 101, an image forming unit 102, a paper feeding device 123, and an operation panel 130. In the case of this example, the paper feeding device 123 includes first to third paper feeding cassettes 122a to 122c, and a sheet presence / absence detection sensor is provided for each of the paper feeding cassettes 122a to 122c serving as recording medium storage units. 131a to 131c are provided in advance (described later).

  When the user prints an original, the original is placed on, for example, the original platen 103, and the size of the paper as an example of the recording medium and the number of printed sheets are operated by operating the buttons on the operation panel 130 provided near the original platen 103. , Initial settings such as print density. Then, when printing is instructed by the print button of the operation panel 130, printing is performed by operating the following units.

  In the image reading unit 101, the light emitted from the light source 104 is reflected by the document placed on the document table 103 and guided to the image sensor 108 by the mirrors 105, 106, and 107. The image sensor 108 photoelectrically converts the received light to generate document image data. In this manner, the image data of the document is read by the image reading unit 101.

  In the image forming unit 102, the photosensitive drum 109 rotates in a predetermined direction at a constant speed, and around the charger 110 in order from the upstream side in the rotation direction (in order of acting on the photosensitive drum 109). An exposure unit 111, a developing unit 112, a transfer unit 113, and the like are arranged. First, the charger 110 uniformly charges the surface of the photosensitive drum 109. The exposure device 111 irradiates the charging unit formed on the photosensitive drum 109 with light according to the image data read by the image reading unit 101 described above, and the electrostatic latent image on the photosensitive drum 109. Form. The developing device 112 causes toner to adhere to the exposed portion of the electrostatic latent image formed by the exposure device 111 to form a toner image on the photosensitive drum 109. The transfer unit 113 transfers the toner image on the photosensitive drum 109 to a sheet. In this way, the series of processes is performed in the image forming unit 102 by rotating the photosensitive drum 109.

  Here, when printing is performed by the image forming unit 102, one paper feed cassette is selected from the first to third paper feed cassettes 122a to 122c, and the sheets are taken out one by one by the pickup rollers 115a to 115c. . The paper taken out from the paper feed cassette 122 is introduced into a paper feed path 125, which is a common path, by feed rollers 124a to 124c provided for the first to third paper feed cassettes 122a to 122c, respectively.

  The sheet introduced into the sheet conveyance path 125 is sent between the photosensitive drum 109 and the transfer unit 113 by the registration roller 117 via the guide roller 116. Next, when the sheet passes between the heating roller 119 and the pressure roller 120 in the fixing device 118, the toner image is fixed to the sheet by heat and the pressing force to the sheet. Then, the sheet that has passed through the fixing device 118 is discharged to the discharge tray 121.

  FIG. 2 is a schematic configuration diagram of a control system of the digital copying machine.

  The digital copying machine 100 includes a CPU (Central Processing Unit) 201, a RAM (Random Access Memory) 202, a ROM (Read Only Memory) 203, an HDD (Hard Disk Drive) 204, and an image reading unit that is driven when printing is performed. A driver 205 corresponding to each drive unit 101, the image forming unit 102, and the sheet feeding device 123 is connected via an internal bus 206. The CPU 201 uses, for example, the RAM 202 as a work area, and executes a program stored in the ROM 203, the HDD 204, or the like. The driver 205 is controlled by exchanging data and commands with the driver 205 based on the execution result.

<Embodiment of the present invention>
Next, referring to FIGS. 3 to 4, the image forming apparatus according to the present invention changes the priority order set for a plurality of paper feed cassettes that feed paper according to the magnitude of the paper feed speed. Will be described.

  FIG. 3 is a functional block diagram showing a control system of the paper feeding device 123 configured based on a program installed in advance in the ROM 203, the HDD 204, and the like.

  As described above, since the paper size is initially set by operating a button on the operation panel 130 provided in the vicinity of the document table 103, the operation panel 130 corresponds to the size designation unit.

  Further, the paper presence / absence detection sensors 131a to 131c are individually provided for the respective paper feed cassettes 122a to 122c, and detect whether or not there is paper in each of the paper feed cassettes 122a to 122c. For this reason, these sheet presence / absence detection sensors 131a to 131c correspond to the feed availability detection means. In this case, various methods for detecting the presence / absence of paper are conceivable. In the embodiment of the present invention, the position of the lift plate provided in each of the paper feed cassettes 122a to 122c is detected. That is, the lift plate can be moved up and down according to the remaining amount of paper in the paper feed cassettes 122a to 122c, so that, for example, when all the paper is sent out, it is in a fully raised position. By detecting the uppermost lift plate, the paper presence / absence detection sensors 131a to 131c can detect the presence / absence of paper. This detection output is given to the priority order determination means 136.

  The speed detection means 132 individually detects a paper feed speed in the vicinity of the paper feed cassette taken out from each of the paper feed cassettes 122a to 122c, and includes a pair of paper passage detection sensors (front side). Paper passage detection sensor 133, rear paper passage detection sensor 134, which will be described later), and a paper feed speed (paper feed speed) calculated based on detection outputs of these paper passage detection sensors 133 and 134. Paper speed calculation means 135.

  Here, the paper passage detection sensors 133a to 133c and 134a to 134c are provided separately for the paper feed cassettes 122a to 122c. As shown in FIG. 1, the paper passage detection sensors 133a to 133c and 134a to 134c are arranged forward and backward along the transport direction of the transport path 125 in the vicinity of the paper feed cassettes 122a to 122c.

  For example, for the first paper feed cassette 122a, the first paper passage detection sensors 133a and 134a are arranged forward and backward along the transport direction of the transport path 125 in the vicinity of the transport roller 124a in the first paper feed cassette 122a. The A sensor disposed forward along the transport direction of the transport path 125 is referred to as a first paper passage detection sensor 133a on the front side, and a sensor disposed rearward along the transport direction of the transport path 125 is referred to as the first paper on the rear side. Let it be a passage detection sensor 134a.

  When the first sheet passage detection sensor 133a on the front side and the first sheet passage detection sensor 134a on the rear side are arranged in the conveyance path 125 near the conveyance roller 124a, the sheet immediately after being fed by the conveyance roller 124a or the like For example, it is possible to directly detect the degree of wear of the transport roller 124a, which is preferable.

  Each of the paper passage detection sensors 133a to 133c and 134a to 134c is, for example, a photocoupler including a light emitting element made of a light emitting diode and a light receiving element made of a phototransistor that receives light from the light emitting element. The In this case, the light emitting element and the light receiving element are provided at positions facing each other with the conveyed paper interposed therebetween. When the paper is conveyed between the light emitting element and the light receiving element, the light from the light emitting element is emitted. Therefore, the paper passage detection sensors 133a to 133c and 134a to 134c can detect that the conveyed paper has passed. If paper passage is detected, a paper detection signal is transmitted to the paper feed speed calculation means 135.

  The paper feed speed calculating means 135 calculates a paper feed speed (m / sec) in the vicinity of the paper feed cassette based on detection outputs (detection signals) from the paper passage detection sensors 133a to 133c and 134a to 134c.

  For example, for a sheet conveyed (fed) from the first sheet feeding cassette 122a, light from the light emitting element of the first sheet passage detection sensor 133a on the front side is blocked by the sheet and is not received by the light receiving element. The time required for the light from the light emitting element of the first paper passage detection sensor 134a on the rear side to be blocked by the paper and not received by the light receiving element, and the distance (m) between the sensors 133a and 134a Based on the above, the paper feed speed (m / sec) of the paper in the vicinity of the paper feed cassette is calculated. When the paper feed speed is calculated, the value of the paper feed speed is given to priority order determination means 136 described later.

  The priority order determination unit 136 determines the paper feed cassettes 122a to 122c based on the paper size information (for example, “A4”) input from the operation panel 130. In addition, when there are a plurality of paper feed cassettes 122a to 122c in which sheets of the same paper size (for example, “A4”) are stored, the priority order determining unit 136 applies the plurality of paper feed cassettes 122a to 122c. To determine the priority order first. That is, if there is no instruction regarding the paper size information from the operation panel 130, the priority order of the paper feed cassettes 122a to 122c is automatically set based on a preset value set in advance.

  When the priority order of the paper feed cassettes 122a to 122c is initially set by the user from the operation panel 130, the priority order determination unit 136 determines the priority order of the paper feed cassettes according to the priority order.

  Further, the priority order determination means 136 changes the priority order initially determined according to the magnitude of the paper feed speed detected by the speed detection means 132 and outputs the detection outputs of the paper presence / absence detection sensors 131a to 131c. Based on this, even when there is no paper in each of the paper feed cassettes 122a to 122c, the priority order determined first is changed. The processing operation for changing the priority will be described in detail later.

  The feeding execution unit 137 is configured to take out a sheet from the highest priority sheet cassette that is the highest priority among the priority levels determined by the priority level determination unit 136 at the time of printing. The paper feed process is executed by driving the driver 205 corresponding to the above.

  Next, the sheet feeding control operation based on the functional block diagram of the control system of the sheet feeding device 123 shown in FIG. 3 will be described with reference to the flowchart shown in FIG. In addition, the code | symbol S means each process step.

  Here, in order to facilitate understanding of the invention, it is assumed that, as an example, all the A4 size sheets are stored in advance in each of the sheet feeding cassettes 122a to 122c. Then, the priority order determination unit 136 sets the first priority order of the sheet cassettes based on automatic setting of priority order based on preset values set in advance by the user or initial setting based on a user instruction from the operation panel 130. It is assumed that the first paper cassette 122a has the highest priority, and the priority is lowered as the second and third paper cassettes 122b and 122c become.

  In this state, the paper feeding device 123 waits for a print instruction from the operation panel 130 (S1), and if there is a print instruction for which no paper size is designated, the priority determination unit 136 determines that the first paper supply with the highest priority is the first. The paper cassette 122a is determined as the highest priority paper feed cassette (S2).

  Next, the priority order determining means 136 determines the presence / absence of paper in the highest priority paper feed cassette 122a based on the detection output of the paper presence / absence detection sensor 131a (S3), and if there is paper in the cassette 122a, priority is given. The order determination unit 136 transmits to the feeding execution unit 137 a command to feed paper from the first paper feed cassette 122a on which paper is present. The feeding execution means 137 that has received the command drives the driver 205 corresponding to the paper feeding cassette 122a so that paper is taken out from the first paper feeding cassette 122a, that is, the highest priority paper feeding cassette 122a. Then, the pickup roller 115a, the transport roller 124a, etc. are driven to execute a paper feed process (S4).

  At that time, the speed detection unit 132 detects the paper feed speed V (m / sec) (S5), and transmits the paper feed speed V (m / sec) to the priority order determination unit 136. Upon receiving the paper feed speed V (m / sec), the priority order determination means 136 acquires a specified value Vsh (m / sec) stored in advance in a predetermined storage means (memory), and feeds the received paper. V (m / sec) is compared with the obtained specified value Vsh (m / sec), and the magnitude relationship between the two is determined. The specified value Vsh (m / sec) is a threshold value set in advance for each of the paper feed cassettes 122a to 122c.

  If the paper feeding speed V (m / sec) is equal to or higher than the specified value Vsh (V ≧ Vsh), the priority order determining means 136 is a pickup roller 115a for picking up paper corresponding to the highest priority paper feeding cassette 122a. It is determined that the conveying parts such as the conveying roller 124a are not yet worn (deteriorated) and the durability is maintained (normally driven), and the highest priority sheet feeding is performed to the feeding execution unit 137. A command to execute paper feeding is transmitted from the cassette 122a. The feeding execution means 137 receives the command from the priority order determination means 136, determines whether or not the necessary number of sheets has been fed in response to the print instruction (S6), and the necessary number of sheets is fed. Then, the paper feed process is terminated (S6 YES → End).

  Any method may be used to determine whether or not the necessary number of sheets has been fed. For example, the number of fed sheets fed from each of the sheet feeding cassettes 122a to 122c is counted by a counter provided in advance. There is a method of determining whether or not the counted number of fed sheets coincides with the number of sheets in the print instruction instructed by the user.

  On the other hand, if the required number of sheets has not been fed, the process returns to S3 and the sheet feeding operation is continued (S6 NO → S3). In other words, the feeding execution unit 137 executes paper feeding with the first paper feeding cassette 122a (the highest priority paper feeding cassette 122a).

  By the way, when the paper in the highest priority paper feed cassette 122a is out of paper in S3, the priority order determination unit 136 lowers the priority order of the current first paper feed cassette 122a to the second higher priority order. The order is changed so that the sheet cassette 122b becomes the highest priority sheet cassette (S7).

  Further, the sheet feeding speed V (m / sec) detected by the speed detecting means 132 in S5 is less than a predetermined value Vsh (m / sec) preset for the first sheet feeding cassette 122a (V <Vsh). ), The priority order determination unit 136 determines that the conveying parts such as the pickup roller 115a and the conveying roller 124a corresponding to the highest priority sheet cassette 122a are deteriorated due to early wear. Also in this case, the order of priority is changed so that the current priority order of the first paper feed cassette 122a is lowered and the second paper feed cassette 122b having the next highest priority order becomes the highest priority paper feed cassette (S7 YES).

  In this way, if the second paper feed cassette 122b is determined as the highest priority paper feed cassette in S7, the same processing as in the case where the first paper feed cassette 122a is determined as the highest priority paper feed cassette in S2 is performed thereafter. Thus, the paper feed process from the second paper feed cassette 122b is executed (S7 to S11).

  On the other hand, if the paper in the top priority paper feed cassette 122b (second paper feed cassette 122b) is out of paper in S8 (NO in S8), or the paper feed speed V detected by the speed detector 132 in S10. Is less than the predetermined value Vsh (V <Vsh) set in advance for the second paper feed cassette 122b (S10 YES), the priority order determination unit 136 lowers the current priority order of the second paper feed cassette 122b. Then, the order is changed so that the third paper feeding cassette 122c having the next highest priority becomes the highest priority paper feeding cassette (S12).

  In this way, if the third paper feed cassette 122c is determined as the highest priority paper feed cassette in S12, thereafter, the same as in the case where the second paper feed cassette 122b is determined as the highest priority paper feed cassette in S7. Paper feed processing from the third paper feed cassette 122c is executed (S13 to S16).

  However, if the sheet in the third sheet cassette 122c, which is the current highest priority sheet cassette in S13, is out of paper (NO in S13), all of the first to third sheet cassettes 122a to 122c are used. The paper may be out of paper. If the paper feed speed V detected by the speed detection means 132 in S15 is less than a predetermined value Vsh (V <Vsh) set in advance for the third paper feed cassette 122c (NO in S15), the first There is a possibility that any of the pick-up rollers 115a to 115c and the conveying parts such as the conveying rollers 124a to 124c corresponding to the third sheet feeding cassettes 122a to 122c may be deteriorated due to early wear.

  Therefore, in this case, the priority order determination unit 136 displays a predetermined warning on, for example, a liquid crystal display unit provided on the operation panel 130 (S17 → End). The predetermined warning display is, for example, a warning display for prompting replenishment of paper or replacement of conveyance parts and a warning display for prompting contact with a service person.

  As described above, in this embodiment, instead of changing the priority order of using the paper feed cassette based on the number of operations of the paper feed cassette as in the prior art, the actual pickup rollers 115a to 115c and the transport rollers are not changed. If the speed detection unit 132 detects a paper feed speed that directly reflects the degree of deterioration of the conveying parts such as 124a to 124c, and the paper feed speed becomes lower than a preset specified value, the priority order The determination unit 136 changes the priority order of using the sheet cassette. As a result, the occurrence of failures can be reduced more reliably than in the prior art, and appropriate paper feeding operations can be continued at any time.

  In addition, paper presence / absence detection sensors 131a to 131c are provided to determine whether or not paper can be fed from the paper cassette. If the paper cannot be fed, the priority order determining unit 136 changes the priority order. It is possible to prevent problems such as inability to print due to running out of paper or interruption of printing.

  In addition, the speed detection unit 132 is configured to calculate the paper feed speed in the vicinity of the paper feed cassette based on the detection outputs from the paper passage detection sensors 133a to 133c and 134a to 134c, but other configurations may be used. . For example, instead of the paper feeding speed in the vicinity of the paper feeding cassette, the passage time T (sec) required to pass between the paper passage detection sensors 133a to 133c and 134a to 134c is adopted, and the priority order determination unit 136 is used. However, it may be configured to determine whether or not the detected passage time T (sec) exceeds a preset specified value Tsh (sec).

  When the passing time T (sec) is less than or equal to the specified value Tsh (sec), the priority order determination unit 136 has still worn the conveying parts such as the pickup roller 115 and the conveying roller 124 corresponding to the highest priority sheet feeding cassette. Judge that there is no. Further, when the passing time T (sec) exceeds the specified value Tsh (sec), the priority order determination means 136 prompts the conveying parts such as the pickup roller 115 and the conveying roller 124 corresponding to the highest priority sheet feeding cassette at an early stage. It is determined that it has deteriorated due to wear.

  When the configuration is employed, the specified value Tsh (sec) is stored in advance in a predetermined storage unit for each of the paper feed cassettes 122a to 122c, and the priority order determination unit 136 executes the feeding. The prescribed value Tsh (sec) corresponding to the paper feed cassette (or paper size) fed by the means 137 is compared with the passage time T (sec) detected by the paper passage detection sensor so as to be judged. Needless to say, make up.

  In the above embodiment, as the first priority of the paper feed cassettes, the first paper feed cassette 122a has the highest priority, and the priority order becomes the second and third paper feed cassettes 122b and 122c. However, the priority may be arbitrarily changed by the user via the operation panel 130. Even when the priority order is changed, it goes without saying that the priority order determination means determines (switches) the priority order of the respective paper feed cassettes 122a to 122c based on the changed priority order and the above-described paper feed speed and the like. Yes.

  In the above embodiment, the first to third three paper feed cassettes 122a to 122c are provided. However, the number of paper feed cassettes is not limited to that. Here, the first to third paper feed cassettes 122a to 122c have been described as preliminarily storing the same A4 size paper, but the present invention is not limited to such an example, and the same. The present invention can be applied when there are a plurality of paper feed cassettes that store paper of a paper size.

  Although the case where the present invention is applied to a digital copying machine as an image forming apparatus has been described here, the present invention is not limited to such a digital copying machine. It can also be applied to devices such as a machine.

  As described above, the image forming apparatus according to the present invention is useful not only for multifunction peripherals but also for copying machines, printers, and the like. The priority order set for a plurality of paper feeding cassettes for feeding paper is set according to the feeding speed. It is effective as an image forming apparatus that can be changed according to the size of the image forming apparatus.

122a 1st paper feed cassette 122b 2nd paper feed cassette 122c 3rd paper feed cassette 123 Paper feed device 125 Paper transport path 131a-131c Paper presence detection sensor (feeding availability detection means)
132 Speed detection means 133a to 133c, 134a to 134c Paper passage detection sensor 135 Paper feed speed calculation means 136 Priority order determination means 137 Feed execution means

Claims (4)

In an image forming apparatus that feeds a recording medium from one of the plurality of recording medium storage units and forms image information on one surface of the recording medium.
A size specifying means for specifying the size of the recording medium;
When there are a plurality of recording medium storage units storing recording media of the size specified by the size specifying unit, a priority order determination unit that determines a priority order for the plurality of recording medium storage units;
A feeding execution unit that feeds the recording medium from the highest priority recording medium storage unit that is the recording medium storage unit with the highest priority among the priority levels determined by the priority level determination unit;
Speed detection means for individually detecting the speed of the recording medium fed from each of the recording medium storage sections in the vicinity of the recording medium storage section;
With
The image forming apparatus according to claim 1, wherein the priority order determining unit changes the priority order of the recording medium storage unit in accordance with the speed of the recording medium detected by the speed detecting unit.   The priority order determining unit, when the speed of the recording medium detected by the speed detecting unit is less than a preset specified value, sets the highest priority recording medium storage unit as a currently executing recording medium storage unit. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is changed to a recording medium storage unit having a higher priority. A feed availability detection unit that determines whether or not the recording medium storage unit can feed,
When the priority determination unit determines that the feeding from the highest priority recording medium storage unit is not possible by the feeding availability detection unit, the priority determination unit sets the highest priority recording medium storage unit as a recording medium currently being executed. The image forming apparatus according to claim 1, wherein the image forming apparatus is changed from a storage unit to a recording medium storage unit having the next highest priority. A pair of front and rear recording medium passage detection sensors arranged along the conveyance direction of the recording medium taken out from each recording medium storage unit;
The speed detection means detects the speed of the recording medium based on a detection signal from the recording medium passage detection sensor and a distance between a pair of front and rear recording medium passage detection sensors. An image forming apparatus according to claim 1.

Images